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MathematicsVectorDot Product & Its Application ( Projection etc.)Easy2 minPYQ_2019
MathematicsEasysingle choice

Leta=2i^+λ1j^+3k^, b=4i^+3-λ2j^+6k^andc=3i^+6j^+λ3-1k^be three vectors such thatb=2aandais perpendicular toc.Then a possible value ofλ1, λ2, λ3is

Options:

Answer:
A
Solution:

Since b=2a, so 3-λ2=2λ1

λ2=3-2λ1   ...1

We know that if two vectors a1i^+b1j^+c1k^ and a2i^+b2j^+c2k^ are perpendicular, then a1a2+b1b2+c1c2=0

Since, a is perpendicular to c so

6+6λ1+3λ3-1=0

6+6λ1+3λ3-3=0

 λ3=-1-2λ1  ...2

From equations 1 and 2, we get

λ1, λ2, λ3=λ1, 3-2λ1, -1-2λ1 where λ1R

 -12, 4, 0 satisfies the above triplet.

Stream:JEESubject:MathematicsTopic:VectorSubtopic:Dot Product & Its Application ( Projection etc.)
2mℹ️ Source: PYQ_2019

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